List of Useful Familiars

Come one come all, tell me and everyone else about good and useful familiars, whether it is their strength, ability, or cool looking. And say how long it took for you~i'll get us started

Jr Boogie of course, continuously heals a large amnt of mp-took only a minute or twoDeath Teddy-continuously heals mp for you and your whole party
Black Kent-continuously heals a small amount of hp and mp for you and your partyKlock-turns you into a crimson (red) shadow
Poison Mushroom- also turns you into a crimson shadowJr Wraith-turns you into a regular shadow..
Dark Stone Golem- turns you into a darker shadowBig spider- raises the drop rate of all items by a large amount
Platoon Chrono- Continuously heals a large amount of party members hp and mpDreamy Ghost- Continuously heals the vitality of summoned familiars (helpful when it isn't summoned, right?)
Book Ghost- Continuously heals a small amount of hp for you and your party; also pulls monsters toward youCaptain- Continuously heals the vitality of summoned familiars for you and your party
Mr. Alli- Cotinuously heals a large amount of hp and mp for you

A lot of the lvl 160+ familiars are awesome and do a lot of damage:

the mutant snail heals a large amount of mp and hp for you and your party
Mutant Ribbon Pig increases drop rate of mesos and items, I think as much as the big spider.